This invention relates to management of the flow of coolant fluid (typically air) to an electrical generator in a vehicle, and in particular to the filtering of such flow which is directed ultimately to the sliding-contact electrical interface region, or zone, in such a generator. While the invention is believed to have applicability in a number of different vehicle settings, a preferred and best mode embodiment of, and manner of practicing, the invention are described herein generally in the context of aircraft, and more particularly in the context of a specific aircraft model wherein the invention has been found to offer significant utility.
In this context, a problem has existed with regard to the operation of certain aircraft relating to unexpectedly early, catastrophic failure of on-board electrical generators—a failure which potentially can be quite dangerous. Not only that, such generators, i.e., those employed in aircraft, can be very expensive pieces of equipment, and a catastrophic failure almost inevitably leads to a requirement for wholesale, costly replacement. The magnitude of this expense problem multiplies appreciably where an aircraft employs more than one electrical generator.
The specific failure herein being referred to involves catastrophic wear in what can be thought of as the electrical sliding-contact zone in a generator of the type mentioned—the zone involving the contact interface between brushes and a commutator, or between brushes and rings. A normal operating condition which is expected in this region is relatively long-term modestly progressive wear of the brushes—components which are expected to require replacement only occasionally, and replacement at a relatively low cost. What is definitively not expected is rapid, noticeable wear of a commutator or rings, let alone early catastrophic wear of these components which are usually and decidedly not intended to require major repair or replacement during the normal, expected working lifetime of a generator. Even more strikingly puzzling is the occurrence of such wear under circumstances wherein there is little evidence of brush wear. Yet, this is exactly the startling manifestation which characterizes the issue to which the present invention is directed.
Until the making of the discovery which has led to the creation of the present invention, experts were baffled by the mentioned wear problem, and indeed even more baffled by the fact that none could discern the cause of the problem. Deciphering of the problem was, to say the least, not intuitive.
Discovery came to me eventually by my taking a very close look at the substantially “non-worn” brushes. This look ultimately enabled me to uncover the culprit. Embedded in the contact face of each examined brush was a dense population of tiny abrasive grit whose presence, I soon determined, effectively reversed the intended, normal wear behavior of the electrical sliding-contact interface region in the failed generator which I was examining. The brushes, with this “illusive” embedded grit in place, were effectively acting in generators like abrader tools—grinding and machining away the working surface(s) of associated commutators/rings. Further examination and contemplation revealed that the primary source of this grit was engine-exhaust particulate content which found its way into the flow of coolant air (fluid) directed toward the contact interface region of the brushes.
Accordingly, and in response to these discoveries, proposed by the present invention is a special ventilation, or coolant, fluid-flow management methodology implemented by a system which effectively eliminates these discovered exhaust-grit problems.
Further elaborating, in the operating environment of an aircraft, and with the system illustrated herein which implements the present invention installed and operating, when the engine is running, and the aircraft is flying, an air intake collects an inflow of air and feeds it into the intake end of a fluid conduit system, the discharge end of which (or ends if more than one electrical generator is/are involved) is/are tightly coupled to (via a fluid-flow connection which closes upon) the electrical sliding-contact (brush, etc.) zone(s) in the generator(s). Intermediate the intake and discharge ends of this special implementing conduit system, in accordance with the invention, is a filter, or a filter structure, which blocks the passage of harmful grit, such as exhaust grit, which may be present in this air flow. Such grit, as I have discussed, puts the electrical sliding-contact zone of an aircraft generator at serious risk—evidenced by surprising degradation of commutator or ring structure in the generator.
Additionally, upstream from this filter structure is an air-flow expansion chamber which acts to retard air-flow velocity, and to expand the cross-sectional area of this retarded flow, thus to improve filtering action. Adjacent the base of the filter structure is a gravity-functioning trap and drain which collects and discharges moisture in the fluid flow adjacent the filter structure.
Installation and operation of this system which carries out the methodology of the invention effectively eliminates the catastrophic wear and failure problem to which the invention is addressed.
These and other important features and advantages which are offered by the methodology of the present invention will become more fully apparent now as the description which shortly follows is read in conjunction with the accompanying drawings.